Bidentate diphosphoramidites with a piperazine group as ligands for hydroformylation

ABSTRACT

The invention relates to Rh, Ru, Co and Ir complexes comprising bidentate diphosphoramidites as ligands and to the use thereof as catalysts for the hydroformylation of olefins. The invention also relates to a process for preparing an aldehyde from an olefin using the complexes or ligands mentioned.

The invention relates to Rh, Ru, Co and Ir complexes comprisingbidentate diphosphoramidites as ligands and to the use thereof ascatalysts for the hydroformylation of olefins. The invention alsorelates to a process for preparing an aldehyde from an olefin using thecomplexes or ligands mentioned.

The reactions between olefin compounds, carbon monoxide and hydrogen inthe presence of a catalyst to give the aldehydes comprising oneadditional carbon atom are known as hydroformylation or oxo synthesis.In terms of volume, hydroformylation is one of the most importanthomogeneous catalyses on the industrial scale. The aldehydes obtainedare important intermediates or end products in the chemical industry (B.Cornelis, W. A. Herrmann, “Applied Homogeneous catalysis withorganometallic compounds”, Vol. 1 & 2, VCH, Weinheim, New York, 1996; R.Franke, D. Selent, A. Börner, Chem. Rev. 2012, 112, 5675).

The catalysts used in hydroformylation are frequently compounds of thetransition metals of group VIII of the Periodic Table of the Elements.Of particular significance here are Rh catalysts. The catalysts furthercomprise suitable ligands, for example compounds from the classes of thephosphines, phosphites and phosphonites, each with trivalent phosphorus.These trivalent phosphorus compounds are usually used to controlactivity and regioselectivity of the catalyst. Since thehydroformylation, except in the case of ethylene as reactant, leads to amixture of isomeric products, namely n-aldehydes (linear aldehydes) andiso-aldehydes (branched aldehydes), aside from the reaction rate andhence yields, the selectivity in the formation of n and iso products isa particularly crucial parameter in the hydroformylation reaction.

Phosphoramidites, i.e. compounds having one or more P—N bonds ratherthan a P—O bond, have to date been used only rarely as ligands inhydroformylation.

Phosphoramidites having a phenyl-phenyl unit have been described in theliterature (J. Mazuela et al., Tetrahedron Asymmetry, 2010, 21(17):21532157, page 2154, compound L2). Van Leeuwen and coworkers were the firstto study monodentate phosphoramidites in hydroformylation (A. van Rooy,D. Burgers, P. C. J. Kamer, P. W. N. M. van Leeuwen, Recl. Tray. Chim.Pays-Bas 1996, 115, 492). Overall, only moderate catalytic propertieswere observed at high ligand/rhodium ratios of up to 1000:1.

WO 2007/031065 A1 discloses the use of chiral phosphoramidites forasymmetric catalyses, but without citing working examples forhydroformylation.

Chiral bidentate ligands each having a phosphoramidite unit have beenused in various forms in asymmetric hydroformylation (J. Mazuela, O.Pàmies, M. Diéguez, L. Palais, S. Rosset, A. Alexakis, Tetrahedron:Asymmetry 2010, 21, 2153-2157; Y. Yan, X. Zhang, J. Am. Chem. Soc. 2006,128, 7198-7202; Z. Hua, V. C. Vassar, H. Choi, I. Ojima, PNAS 2004, 13,5411-5416).

The problem addressed by the present invention is that of providingnovel ligands and catalysts for hydroformylation, which assure a highyield and permit control of the n/iso ratio.

This problem is solved by a complex comprising Rh, Ru, Co or Ir and acompound of one of the general formulae (I) and (II)

where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵,R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰ are each independently selected from —H,—(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl,halogen, —COO—(C₁-C₁₂)-alkyl, —CONH—(C₁-C₁₂)-alkyl, —CO—(C₁-C₁₂)-alkyl,—CO—(C₆-C₂₀)-aryl, —COOH, —OH, —N[(C₁-C₁₂)-alkyl]₂;and R^(2′), R^(3′), R^(4′), R^(5′), R^(6′), R^(7′), R^(8′), R^(9′),R^(12′), R^(13′), R^(14′), R^(15′), R^(16′), R^(17′), R^(18′), R^(19′)are each independently selected from —H, —(C₁-C₁₂)-alkyl,—O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl, halogen,—COO—(C₁-C₁₂)-alkyl, —CONH—(C₁-C₁₂)-alkyl, —CO—(C₁-C₁₂)-alkyl,—CO—(C₆-C₂₀)-aryl, —COOH, —OH, —N[(C₁-C₁₂)-alkyl]₂.

The complexes according to the invention are suitable as catalysts forthe hydroformylation of olefins, for example of octenes or pentene, withwhich high yields can be achieved. In addition, through suitableselection of the catalysts, it is possible to control the n/iso ratio.

The catalysts according to the invention feature the compounds of theformulae (I) and (II), which have not been used to date in thehydroformylation of olefins.

Rhodium complexes are particularly suitable catalysts forhydroformylation. Preferably, the catalysts according to the inventiontherefore comprise Rh.

R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰ are preferably each independently selected from —H,—(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl,-halogen.

In a preferred embodiment, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹,R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰ are each independentlyselected from —H, —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl,—O—(C₆-C₂₀)-aryl.

In a particularly preferred embodiment, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸,R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰ are eachindependently selected from —H, —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl.

In a further particularly preferred embodiment, R¹, R², R³, R⁴, R⁵, R⁶,R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰ areeach independently selected from —H, —(C₁-C₆)-alkyl.

R^(2′), R^(3′), R^(4′), R^(5′), R^(6′), R^(7′), R^(8′), R^(9′), R^(12′),R^(13′), R^(14′), R^(15′), R^(16′), R^(17′), R^(18′), R^(19′) arepreferably each independently selected from —H, —(C₁-C₁₂)-alkyl,—O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl, -halogen.

In a preferred embodiment, R^(2′), R^(3′), R^(4′), R^(5′), R^(6′),R^(7′), R^(8′), R^(9′), R^(12′), R^(13′), R^(14′), R^(15′), R^(16′),R^(17′), R^(18′), R^(19′) are each independently selected from —H,—(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl.

In a particularly preferred embodiment, R^(2′), R^(3′), R^(4′), R^(5′),R^(6′), R^(7′), R^(8′), R^(9′), R^(12′), R^(13′), R^(14′), R^(15′),R^(16′), R^(17′), R^(18′), R^(19′) are each independently selected from—H, —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl.

In a further particularly preferred embodiment, R^(2′), R^(3′), R^(4′),R^(5′), R^(6′), R^(7′), R^(8′), R^(9′), R^(12′), R^(13′), R^(14′),R^(15′), R^(16′), R^(17′), R^(18′), R^(19′) are each independentlyselected from —H, —(C₁-C₆)-alkyl.

In a further particularly preferred embodiment, R¹, R², R⁴, R⁷, R⁹, R¹⁰,R¹¹, R¹², R¹⁴, R¹⁷, R¹⁹, R²⁰ are each H.

In a further particularly preferred embodiment, R^(2′), R^(4′), R^(7′),R^(9′), R^(12′), R^(14′), R^(17′), R^(19′) are each H.

In a further particularly preferred embodiment, the benzene or dibenzenerings of the ligands (I) and (II) are each substituted in the orthoand/or para positions.

In one embodiment, the compound has the general formula (I).

In a further embodiment, the compound has the general formula (II).

The catalysts according to the invention thus preferably comprise Rh,Ru, Co or Ir, but especially Ir, and a compound of one of the formulae(III) and (IV):

where R³, R⁵, R⁶, R⁸, R¹³, R¹⁵, R¹⁶, R¹⁸ are each independently selectedfrom —H, —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl,—O—(C₆-C₂₀)-aryl, halogen, —COO—(C₁-C₁₂)-alkyl, —CONH—(C₁-C₁₂)-alkyl,—CO—(C₁-C₁₂)-alkyl, —CO—(C₆-C₂₀)-aryl, —COOH, —OH, —N[(C₁-C₁₂)-alkyl]₂;and R^(3′), R^(5′), R^(6′), R^(8′), R^(13′), R^(15′), R^(16′), R^(18′)are each independently selected from —H, —(C₁-C₁₂)-alkyl,—O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl, halogen,—COO—(C₁-C₁₂)-alkyl, —CONH—(C₁-C₁₂)-alkyl, —CO—(C₁-C₁₂)-alkyl,—CO—(C₆-C₂₀)-aryl, —COOH, —OH, —N[(C₁-C₁₂)-alkyl]₂.

More preferably, R³, R⁵, R⁶, R⁸, R¹³, R¹⁵, R¹⁶, R¹⁸ in this case areeach independently selected from —H, —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl.

More preferably, R^(3′), R^(5′), R^(6′), R^(8′), R^(13′), R^(15′),R^(16′), R¹⁸ in this case are each independently selected from —H,—(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl.

In one embodiment, the compound has the general formula (III).

In a further embodiment, the compound has the general formula (IV).

It has been found that the following compounds (4) to (7) areparticularly suitable ligands of the formulae (I) and (II). Thecomplexes according to the invention therefore preferably comprise oneof the compounds (4), (5), (6) and (7):

In one embodiment, the complexes are a complex of the formula 8 or 9:

The invention also relates to the use of the complex according to theinvention or of the compounds of one of the formulae (I) and (II) forcatalysis of a hydroformylation reaction. More particularly, thisrelates to the hydroformylation of olefins having 2 to 20 carbon atoms,preferably 2 to 12 carbon atoms, more preferably 4 to 10 carbon atoms.

The invention also relates to a process for preparing an aldehyde,comprising the process steps of:

a) initially charging an olefin,b) adding a complex according to the invention ora compound of one of the formulae (I) and (II) and a catalyst precursorcomprising an Rh, Ru, Co or Ir complex,c) feeding in hydrogen and carbon monoxide,d) heating the reaction mixture, with conversion of the olefin to analdehyde. In this process, process steps a) to d) can be effected in anydesired sequence.

The reactants in the process according to the invention are olefins ormixtures of olefins, especially of olefins having 2 to 20 carbon atoms,preferably 2 to 12 carbon atoms, more preferably 4 to 10 carbon atoms.

Particularly suitable olefins are monoolefins having a terminalcarbon-carbon double bond.

Suitable olefins are, for example 1-propene, 1- or 2-pentene,2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, 1-, 2- or3-hexene, the C₆ olefin mixture obtained in the dimerization of propene(dipropene), heptenes, 2- or 3-methyl-1-hexenes, octenes,2-methylheptenes, 3-methylheptenes, 5-methyl-2-heptene,6-methyl-2-heptene, 2-ethyl-1-hexene, the C₈ olefin mixture obtained inthe dimerization of butenes (dibutene), nonenes, 2- or 3-methyloctenes,the C₉ olefin mixture obtained in the trimerization of propene(tripropene), decenes, 2-ethyl-1-octene, dodecenes, the C₁₂ olefinmixture obtained in the tetramerization or the trimerization of butenes(tetrapropene or tributene), tetradecenes, hexadecenes, the C₁₆ olefinmixture obtained in the tetramerization of butenes (tetrabutane), andolefin mixtures prepared by cooligomerization of olefins havingdifferent numbers of carbon atoms (preferably 2 to 4).

In a preferred variant of the process, the catalyst used is a complexaccording to the invention comprising Rh.

The catalyst complex can also be formed in situ, by adding, in step b),a compound of one of the formulae (I) and (II) which functions asligand, and a catalyst precursor comprising an Rh, Ru, Co or Ir complex.A ligand exchange reaction between the ligands of the catalyst precursorand the compound of one of the formulae (I) and (II) forms the catalystcomplex according to the invention here.

In this case, it is also possible to use an excess of ligands, suchthat, after formation of the catalytic complex, not necessarily everyligand is in the form of a ligand-metal complex; instead, a portion ofligands added is present in unbound form in the reaction mixture.

The molar ratio of the compound of one of the formulae (I) and (II) tothe metal atom of the catalyst precursor is preferably in the range from40:1 to 1:1, preferably 20:1 to 1:1, more preferably 5:1 to 1:1.

The catalyst precursor is preferably an Rh, Ru, Co or Ir complexcomprising a ligand selected from acetylacetonate (acac), acetate (OAc)and chloride. More preferably, the catalyst precursor is an Rh complex.

Preferably, the catalyst precursor comprises rhodium carbonyls, rhodiumnitrate, rhodium chloride, Rh(CO)₂(acac) (acac=acetylacetonate), rhodiumacetate or rhodium carboxylates, for example rhodium octanoate, morepreferably Rh(acac)(CO)₂.

The conversion of the olefin to the aldehyde preferably takes place at atemperature of 80° C. to 200° C., preferably 90° C. to 180° C., morepreferably 100° C. to 160° C.

The conversion of the olefin to the aldehyde preferably takes place at apressure of 1 bar to 300 bar, preferably 15 bar to 250 bar, morepreferably 15 bar to 50 bar.

In the context of the invention, the expression “—(C₁-C₁₂)-alkyl”encompasses straight-chain and branched alkyl groups. Preferably, thesegroups are unsubstituted straight-chain or branched —(C₁-C₈)-alkylgroups and most preferably —(C₁-C₆)-alkyl groups. Examples of—(C₁-C₁₂)-alkyl groups are especially methyl, ethyl, propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl,2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl,2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 2-hexyl, 2-methylpentyl,3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl,2,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl,3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl,1-ethylbutyl, 1-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl,2-ethylpentyl, 1-propylbutyl, n-octyl, 2-ethylhexyl, 2-propylheptyl,nonyl, decyl.

Halogen as substituent on alkyl or aryl includes fluorine, chlorine,bromine and iodine, particular preference being given to chlorine andfluorine.

All elucidations relating to the expression —(C₁-C₁₂)-alkyl in theaforementioned structures of the selenaphosphites and selenodiarylsaccording to the invention also apply to the alkyl groups in—O—(C₁-C₁₂)-alkyl, that is, in —(C₁-C₁₂)-alkoxy.

Preference is given to unsubstituted straight-chain or branched—(C₁-C₆)-alkoxy groups.

Substituted —(C₁-C₁₂)-alkyl groups and substituted —(C₁-C₁₂)-alkoxygroups in the aforementioned structures of the selenaphosphites andselenodiaryls may have one or more substituents, depending on theirchain length. The substituents are preferably each independentlyselected from:

—(C₃-C₁₂)-cycloalkyl, —(C₃-C₁₂)-heterocycloalkyl, —(C₆-C₂₀)-aryl,fluorine, chlorine, cyano, formyl, acyl or alkoxycarbonyl. Thisdefinition applies to all substituted alkyl or alkoxy groups of thepresent invention.

Preference is given to unsubstituted —O—(C₆-C₂₀)— groups.

In the context of the present invention, the expression “—(C₆-C₂₀)-aryland —(C₆-C₂₀)-aryl-(C₆-C₂₀)-aryl-” encompasses mono- or polycyclicaromatic hydrocarbyl radicals. These have 6 to 20 ring atoms, morepreferably 6 to 14 ring atoms, especially 6 to 10 ring atoms. Aryl ispreferably —(C₆-C₁₀)-aryl and

—(C₆-C₁₀)-aryl—(C₆-C₁₀)-aryl-. Aryl is especially phenyl, naphthyl,indenyl, fluorenyl, anthracenyl, phenanthrenyl, naphthacenyl, chrysenyl,pyrenyl, coronenyl. More particularly, aryl is phenyl, naphthyl andanthracenyl.

The invention is further illustrated in detail below by examples withoutthe invention being limited to the working examples.

EXAMPLES

The examples which follow illustrate the invention.

General Methods

All reactions were conducted under an inert atmosphere (5.0 argon) usingstandard Schlenk methodology. The solvents were dried by conventionalmethods and distilled under argon. If possible, the reactions weremonitored by NMR spectroscopy. The yields reported below are isolatedyields; melting points are uncorrected.

NMR spectra were recorded at room temperature with a Bruker AV 300 or AV400 MHz spectrometer. The chemical shifts are in ppm relative to TMS;solvent signals (dichloromethane, δ_(H)=5.32 ppm, δ_(C)=53.8 ppm;tetrahydrofuran δ_(H)=3.58; 1.73 ppm; δ_(C)=67.5; 25.37 ppm) were usedas secondary reference for ¹H and ¹³C NMR spectroscopy. For the ³¹P NMRspectra, external H₃PO₄ was used as standard.

The IR spectra were recorded on a Nicolet 380 FT-IR. High-resolutionmass spectrometry (HRMS) was recorded on an Agilent 6210 E1969A TOFspectrometer. Only the measurements with an average deviation from thetheoretical mass of ±2 mDa were considered to be correct.

X-ray diffraction data of single crystals of the compounds 6 wererecorded on a Bruker APEX II Kappa Duo diffractometer. The structureswere solved by direct methods by means of the SHELXS-97 program (G. M.Sheldrick, Acta. Crystallogr. Sect. A. 64 (2008) 112-122) and refined bythe full matrix least squares method on F² by means of the SHELXL-2014program (G. M. Sheldrick, Acta. Crystallogr. Sect. C. 71 (2015) 3-8).

Gas chromatography was conducted on an HP 5890 Series II using a PONAcolumn (0.5 mm; length 50 m; diameter 0.2 mm). All reactions weremonitored by thin layer chromatography (silica gel 60, F₂₅₄, E. MerckKGAG). The solvent systems used (v/v) were: hexane-CH₂Cl₂ 1:1 (A₁), or5:1 (A₂); hexane-EtOAc 99:1 (B₁). Detection was effected by UVfluorescence (λ=254 nm, λ=365 nm).

Preparative flash chromatography was conducted by using packed columns(silica gel, RediSep) with a CombiFlash R_(f) system (Teledyne ISCO).

Synthesis of the Phosphorochloridites 1-3

The phosphorochloridites 1 (E. Benetskiy, S. Lühr, M. Vilches-Herrera,D. Selent, H. Jiao, L. Domke, K. Dyballa, R. Franke, A. Börner, ACSCatal. 4 (2014) 2130-2136), 2 [V. N. Tsarev, A. A. Kabro, S. K. Moiseev,V. N. Kalinin, O. G. Bondarev, V. A. Davankov, K. N. Gavrilov, Russ.Chem. Bull., Int. Ed. 53 (2004) 814-818; D. J. Frank, A. Franzke, A.Pfaltz, Chem. Eur. J. 19 (2013) 2405-2415; O. Lot, I. Suisse1, A.Mortreux, F. Agbossou, J. Mol. Catal. A: Chem. 164 (2000) 125-130] and 3(L. P. J. Burton, U.S. Pat. No. 4,739,000 A (1988)) were preparedaccording to the literature.

Synthesis of the Phosphoramidites 4, 5 and 6

For general procedure see B. L. Feringa, J. F. Teichert, Angew. Chem.Int. Ed. 49 (2010) 2486-2528; E. Balaraman, K. C. Kumara Swamy,Tetrahedron: Asymmetry 18 (2007) 2037-2048; M. Rodriguez i Zubiri, A. M.Z. Slawin, M. Wainwright, J. Derek Woollins, Polyhedron. 21 (2002)1729-1736.

A solution of the corresponding phosphorochloridites (2.0 mmol) in THF(20 ml) was added dropwise over a period of 30 min to an ice-cooledsolution of the amine (1.0 mmol) and triethylamine (4.0 mmol) in THF (30ml). After 15 min, the solution was allowed to warm up gradually to roomtemperature and the stirring was continued overnight; during this time,triethylammonium hydrochloride precipitated out of the colourlesssolution and was removable by filtration. After the solvent had beenremoved under reduced pressure, the crude product was purified by flashchromatography, and it was possible to isolate the amidites as whitesolids. All ligands are readily available and can be prepared on thegram scale.

1,4-Bis(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]clioxaphosphepin-6-yl)piperazine(4)

See a) M. Rasberger, EP 5500 A1. (1979); b) M. Rasberger, U.S. Pat. No.4,301,061 A. (1981); c) T. Shinya, P. Yukihiro, S. Motohiko, F. Kanako,S. Manji, Y. Tetsuo, Jpn. Kokai Tokkyo Koho, J P 07070158 A. (1995).

Yield: 67%; white crystals; m.p. 341-343° C. (decomposition); R_(f) 0.42(system B₁); ³¹P-NMR (CD₂Cl₂): δ 143.48; ¹H-NMR (CD₂Cl₂; 300.13 MHz): δ7.41; 7.13 (2br.s, 8H, ArH), 3.10-2.75 (m, 8H, NCH₂); 1.47; 1.34 (2s,72H, C(CH₃)₃); ¹³C-NMR (OD₂Cl₂; 75.46 MHz): δ 147.48 (d, ²J_(C,P)=5.68Hz; ArC—OP); 146.49; 140.19; 132.88 (ArC—C), 126.41; 124.59 (ArCH);undetectable (NCH₂); 35.68; 34.87 (C(CH₃)₃); 31.61; 31.06; 31.02(C(CH₃)₃); HRMS (ESI) calc'd for [M+H]⁺ C₆₀H₈₈N₂O₄P₂: 963.6292; found:963.6293; calc'd for [M+Na]⁺ C₆₀H₈₈N₂O₄P₂: 985.6112; found: 985.6117;elemental analysis calc. for C₆₀H₈₈N₂O₄P₂(%): C, 74.81 (75.06); H, 9.21(9.26); N, 2.91 (2.72); P, 6.42 (6.32).

1,4-Bis(dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)piperazine (5)

Yield: 55%; white crystals; m.p. 209-210° C.; R_(f) 0.35 (system A₁);³¹P-NMR (CD₂Cl₂): δ 146.0; ¹H-NMR (CD₂Cl₂; 300.13 MHz): δ 7.49 (dd, 4H,J_(H,H)=7.64 Hz; J_(H,H)=1.74 Hz; ArH); 7.42-7.37; 7.31-7.19 (2m, 12H,ArH); 3.05-3.03 (m, 8H, NCH₂); ¹³C-NMR (CD₂Cl₂; 75.46 MHz): δ 151.56 (d,²J_(C,P)=4.37 Hz; ArC—OP); 131.38 (d, ³J_(C,P)=2.91 Hz; ArC—C); 130.02;129.65; 125.06; 122.21 (ArCH); 45.90-45.58 (m, ²J_(C,P)=18.94 Hz;³J_(C,P)=4.37 Hz; NCH₂); HRMS (ESI) calc'd for [M+H]⁺ C₂₈H₂₄N₂O₄P₂:515.1284; found: 515.1283; elemental analysis calc. for C₂₈H₂₄N₂O₄P₂(%):C, 65.37 (65.51); H, 4.70 (4.73); N, 5.45 (5.52); P, 12.04 (11.88).

Tetrakis(2,4-di-tert-butylphenyl)piperazine-1,4-diyl bis(phosphonite)(6)

See M. Fryberg, V. Weiss, EP 0070254 A1. (1983).

Yield: 62.5%; white crystals; m.p. 174-175° C.; R_(f) 0.2 (system A₂);³¹P-NMR (CD₂Cl₂): δ 133.3; ¹H-NMR (OD₂Cl₂; 300.13 MHz): δ 7.39 (d, 4H,J_(H,H)=2.36 Hz; ArH); 7.10 (qd, 8H, 8.40 Hz; J_(H H)=2.40 Hz; ArH);3.37-3.36 (m, 8H, NCH₂); 1.43; 1.33 (2s, 72H, C(CH₃)₃); ¹³C-NMR (CD₂Cl₂;100.61 MHz): δ 151.10 (d, ²J_(C,P)=8.37 Hz; ArC—OP); 144.85; 131.33(ArC—C); 124.66; 123.73 (ArCH); 117.79 (d, ³J_(C,P)=22.31 Hz; ArC—H);45.11-44.86 (m, ²J_(C,P)=19.52 Hz; ³J_(C,P)=5.58 Hz; NCH₂); 35.33; 34.67(C(CH₃)₃); 31.61; 30.23 (C(CH₃)₃); HRMS (ESI) calc'd for [M+H]⁺C₆₀H₉₂N₂O₄P₂: 967.6605; found: 967.6622; calc'd for [M+Na]⁺C₆₀H₉₂N₂O₄P₂: 989.6425; found: 989.6432; elemental analysis calc. forC₆₀H₉₂N₂O₄P₂ (%): C, 74.50 (74.53); H, 9.59 (9.55); N, 2.90 (2.91); P,6.40 (6.46). Single crystals were obtained by gradually evaporating aconcentrated solution of dichloromethane.

Synthesis of Phosphoramidite 7: General Method

See Y. H. Choi, J. Y. Choi, H. Y. Yang, Y. H. Kim, Tetrahedron:Asymmetry. 13 (2002) 801-804; M. Vuagnoux-d'Augustin, A. Alexakis, Chem.Eur. J. 13 (2007) 9647-9662; S. Lühr, J. Holz, A. Börner, Chem Cat Chem.3 (2011) 1708-1730.

A solution of the amine (1.0 mmol) and triethylamine (5.0 mmol) in THF(5 ml) is added dropwise to phosphorus trichloride (2.0 mmol) at 0° C.The reaction mixture was left to warm up to room temperature and to stirfor a further three hours. The resulting HCl gas was driven out of thereaction vessel using a gentle argon stream. The clear solution wasconcentrated and dried azeotropically with toluene (three times). Theresulting residue was used directly in the next step without furtherpurification. The oily crude product was dissolved in THF (20 ml) andcooled to 0° C. A solution of phenol (4.0 mmol) and triethylamine (5.0mmol) in THF (5 ml) was then added dropwise to the stirred solution. Thereaction mixture was brought gradually to room temperature and thestirring was continued overnight. The precipitate was filtered off andthe solution obtained was concentrated. The crude products were purifiedby flash chromatography and the pure amidites 7 were obtained as a whitesolid.

Tetraphenylpiperazine-1,4-diylbis(phosphonite) (7)

See Zh. Beishekeev, B. Ashimbaeva, T. Chyntemirova, K. Dzhundubaev, Zh.Anyrova, T. Toktobekova, Izvestiya Akademii Nauk Kirgizskoi SSR. 1(1980) 37-39.

Yield: 61%; white crystals; m.p. 110-111° C.; R_(f) 0.40 (system A₁); ³¹P-NMR (CD₂Cl₂): δ 136.94; ¹H-NMR (CD₂Cl₂; 300.13 MHz): δ 7.35-7.28;7.12-7.04 (2m, 20H, ArH); 3.25-3.22 (m, 8H, NCH₂); ¹³C-NMR (CD₂Cl₂;75.46 MHz): δ 154.01 (d, ²J_(C,P)=6.25 Hz; ArC—OP); 130.02; 123.55;120.54; 120.41 (ArCH, 2 signals are isochronous); 44.94-44.63 (m,²J_(C,P)=18.21 Hz; ³J_(C,P)=4.79 Hz; NCH₂); HRMS (ESI) calc'd for [M+H]⁺C₂₈H₂₈N₂O₄P₂: 519.15971; found: 519.16035; calc'd for [M+Na]⁺C₂₈H₂₈N₂O₄P₂: 541.14165; found: 541.1416; elemental analysis calc. forC₂₈H₂₈N₂O₄P₂ (%): C, 64.86 (64.89); H, 5.44 (5.45); N, 5.40 (5.59); P,11.95 (11.83).

Synthesis of Rh (I) Complexes 8 and 9

To a solution of Rh(acac)(CO)₂ (0.2 mmol) in toluene (5 ml) is addeddropwise, at room temperature while stirring, a solution of the ligand(0.1 mmol) in toluene (5 ml) within 10 min. On completion of addition,the reaction solution is stirred for two hours and concentrated underreduced pressure. By washing the residue with hexane (6 ml) and dryingat 60° C. over three hours, the spectroscopically pure products areobtained.

FIG. 5. Rh complexes 8 and 9

[Rh(Acac)(CO)]₂(4) Complex (8)

Yield: quantitative; yellow powder; ³¹P-NMR (CD₂Cl₂): δ 141.80 (br. d,¹J_(P,Rh)=276.95 Hz); IR: ν (CO) 2000.3 cm⁻¹; ¹H-NMR (THF-d8; 300.13MHz): δ 7.37 (d, 4H, J_(H,H)=1.83 Hz; ArH); 7.04 (br. s, 4H,J_(H,H)=1.64 Hz; ArH); 5.34 (s, 2H, CH_(acac)); 3.03-2.28 (m, 8H, NCH₂);1.83 (s, 6H, Me_(acac)); 1.77 (br. s, 6H, Me_(acac)); 1.41; 1.23 (2s,72H, C(CH₃)₃); ¹³C-NMR (THF-d8; 75.46 MHz): δ 188.56; 187.58 (2d,J_(C,Rh)=29.15 Hz; CO); 187.34; 183.73 (CO_(acac)); 146.28 (ArC—OP);145.87 (d, J_(C,P)=9.48 Hz; ArC—C); 149.51; 131.28; 127.16; 124.22(ArCH); 99.54 (CH_(acac)); undetectable (NCH₂); 34.95; 33.89 (C(CH₃)₃);30.62; 30.39 (C(CH₃)₃); 26.51 (Me_(acac)); 26.02 (d, ⁵J_(C,Rh)=8.16 Hz;Me_(acac)); HRMS (ESI) calc'd for [M+Na-2H]⁺ C₇₂H₁₀₂N₂O₁₀P₂Rh₂:1445.2015; found: 1445.50111; elemental analysis calc. forC₇₂H₁₀₄N₂O₁₀P₂Rh₂ (%): C, 60.67 (60.82); H, 7.35 (7.33); N, 1.97 (1.93);P, 4.35 (4.45); Rh, 14.44 (14.30).

[Rh(Acac)(CO)]₂(6) Complex (9)

Yield: quantitative; yellow powder; ³¹P-NMR (CD₂Cl₂): δ 128.70 (d,¹J_(P,Rh)=258.56 Hz); IR: ν (CO) 1992.2 cm⁻¹; ¹H-NMR (CD₂Cl₂; 300.13MHz): δ 7.49 (dd, 4H, J_(H,H)=8.45 Hz; J_(H,H)=1.41 Hz; ArH); 7.31 (br.d, 4H, J_(H,H)=1.64 Hz; ArH); 7.04 (dd, 4H, J_(H,H)=8.45 Hz;J_(H,H)=2.46 Hz; ArH); 5.35 (s, 2H, CH_(acac)); 3.70-3.04 (m, 8H, NCH₂);1.89; 1.52 (2s, 12H, Me_(acac)); 1.29; 1.23 (2s, 72H, C(CH₃)₃); ¹³C-NMR(CD₂Cl₂; 75.46 MHz): δ 188.56; 187.58 (2d, J_(C,Rh)=31.58 Hz; CO);188.29; 185.84 (CO_(acac)); 149.53 (d, ²J_(C,P)=3.20 Hz; ArC—OP); 146.01(ArC—C); 138.89 (d, ³J_(C,P)=5.88 Hz; ArC—C); 124.77; 123.35 (ArCH);119.75 (J_(C,P)=9.61 Hz; ArCH); 101.03 (CH_(acac)); 46.86 (NCH₂); 35.31;34.77 (C(CH₃)₃); 31.68; 30.32 (C(CH₃)₃); 27.60 (d, ⁵J_(C,Rh)=7.68 Hz;Me_(acac)); 26.84 (Me_(acac)); HRMS (ESI) calc'd for [M+Na-2H]⁺C₇₂H₁₀₆N₂O₄P₂Rh₂: 1449.5325; found: 1449.5297; elemental analysis calc.for C₇₂H₁₀₈N₂O₄P₂Rh₂ (%): C, 60.50 (60.62); H, 7.62 (7.52); N, 1.96(1.91); P, 4.33 (4.40); Rh, 14.40 (14.36).

Hydroformylation Methods

The hydroformylation experiments were conducted in a 200 ml autoclaveequipped with a thermocouple, a Bronkhorst HITEC mass flow meter and aBronkhorst pressure regulator, at 120° C. and a pressure of 50 bar ofsynthesis gas (99.997%; CO/H₂=1:1). The reaction was effected at aconstant pressure over a period of four hours. The autoclave togetherwith the storage vessel for the olefin addition was purged repeatedlywith argon before the catalyst solution (=metal complex+ligand+solvent)was introduced into the reactor and the olefin to the reservoir vessel(argon countercurrent). In a typical experiment, olefin (15 ml) andcatalyst solution (41 ml) were used with olefin/rhodium ratio of 2000/1.The catalyst solution was heated to the desired reaction temperatureunder synthesis gas for 30 minutes. After the addition of olefin, thepressure was kept at 50 bar and the gas consumption was measured with amass flow meter. After four hours, the autoclave was cooled down to roomtemperature and the pressure was released. The product analysis waseffected by gas chromatography; for this purpose, the reaction solution(1 ml) was diluted with n-pentane (10 ml) and toluene was used asinternal standard.

Experiments were conducted in each case with n-octenes (EVONIKIndustries AG, octene isomer mixture of 1-octene: 3.3%;cis-+trans-2-octene: 48.5%; cis-+trans-3-octene: 29.2%;cis-+trans-4-octene: 16.4%; structurally isomeric octenes: 2.6%),1-octene or 2-pentene as reactants. The yields and n/iso ratios achievedare shown in Tables 1 to 3. As apparent from the experimental results,the complexes according to the invention are suitable as catalysts forthe hydroformylation of olefins, with which virtually quantitativeyields can be achieved. Moreover, it is possible via selection of theligands according to the invention to achieve a high n or isoselectivity.

TABLE 1 Hydroformylation of n-octene with the bidentatediphosphoramidites 4 and 6 n selectivity Entry Ligand L/Rh Yield (%) (%)1 4 2 98.9 18.7 2 6 2 91.7 16.9

TABLE 2 Hydroformylation of 1-octene with the bidentatediphosphoramidites 4, 5 and 7 n selectivity Entry Ligand L/Rh Yield (%)(%) 1 4 2 99.6 52.8 2 5 2 85.3 75.2 3 7 2 28.5 69.0

TABLE 3 Hydroformylation of 2-pentene with the bidentatediphosphoramidites 5 and 6 n selectivity Entry Ligand L/Rh Yield (%) (%)1 5 2 59.4 20.3 2 6 2 100 36.6

As the results show, the n/iso ratio can be controlled with the aid ofthe novel ligands.

1. Complex comprising Rh, Ru, Co or Ir and a compound of one of thegeneral formulae (I) and (II)

where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵,R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰ are each independently selected from —H,—(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl,halogen, —COO—(C₁-C₁₂)-alkyl, —CONH—(C₁-C₁₂)-alkyl, —CO—(C₁-C₁₂)-alkyl,—CO—(C₆-C₂₀)-aryl, —COOH, —OH, —N[(C₁-C₁₂)-alkyl]₂; and R^(2′), R^(3′),R^(4′), R^(5′), R^(6′), R^(7′), R^(8′), R^(9′), R^(12′), R^(13′),R^(14′), R^(15′), R^(16′), R^(17′), R^(18′), R^(19′) are eachindependently selected from —H, —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl,—(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl, halogen, —COO—(C₁-C₁₂)-alkyl,—CONH—(C₁-C₁₂)-alkyl, —CO—(C₁-C₁₂)-alkyl, —CO—(C₆-C₂₀)-aryl, —COOH, —OH,—N[(C₁-C₁₂)-alkyl]₂.
 2. Complex according to claim 1, comprising Rh. 3.Compound according to claim 1, characterized in that R¹, R², R³, R⁴, R⁵,R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰are each independently selected from —H, —(C₁-C₁₂)-alkyl,—O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl, -halogen. 4.Complex according to claim 1, characterized in that R¹, R², R³, R⁴, R⁵,R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰are each independently selected from —H, —(C₁-C₁₂)-alkyl,—O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl.
 5. Complexaccording to claim 1, characterized in that R^(2′), R^(3′), R^(4′),R^(5′), R^(6′), R^(7′), R^(8′), R^(9′), R^(12′), R^(13′), R^(14′),R^(15′), R^(16′), R^(17′), R^(18′), R^(19′) are each independentlyselected from —H, —O—(C₁-C₁₂)-alkyl, —(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl,-halogen.
 6. Complex according to claim 1, characterized in that R^(2′),R^(3′), R^(4′), R^(5′), R^(6′), R^(7′), R^(8′), R^(9′), R^(12′),R^(13′), R^(14′), R^(15′), R^(16′), R^(17′), R^(18′), R^(19′) are eachindependently selected from —H, —(C₁-C₁₂)-alkyl, —O—(C₁-C₁₂)-alkyl,—(C₆-C₂₀)-aryl, —O—(C₆-C₂₀)-aryl.
 7. Complex according to claim 1,characterized in that R¹, R², R⁴, R⁷, R⁹, R¹⁰, R¹¹, R¹², R¹⁴, R¹⁷, R¹⁹,R²⁰ are each H.
 8. Complex according to claim 1, characterized in thatR^(2′), R^(4′), R^(7′), R^(9′), R^(12′), R^(14′), R^(17′), R¹⁹ are eachH.
 9. Complex according to claim 1, characterized in that the compoundof one of the formulae (I) and (II) is selected from the compounds (4),(5), (6) and (7)


10. Use of a complex according to claim 1 for catalysis of ahydroformylation reaction.
 11. Process for preparing an aldehyde,comprising the process steps of: a) initially charging an olefin, b)adding a complex according to claim 1 and a catalyst precursorcomprising an Rh, Ru, Co or Ir complex, c) feeding in hydrogen andcarbon monoxide, d) heating the reaction mixture, with conversion of theolefin to an aldehyde.
 12. Process according to claim 11, characterizedin that the catalyst precursor comprises a ligand selected fromacetylacetonate, acetate and chloride.
 13. Process according to claim11, characterized in that the catalyst precursor is Rh(acac)(CO)₂. 14.Process for preparing an aldehyde, comprising the process steps of: a)initially charging an olefin, b) adding a compound of one of theformulae (I) and (II) according to claim 1 and a catalyst precursorcomprising an Rh, Ru, Co or Ir complex, c) feeding in hydrogen andcarbon monoxide, d) heating the reaction mixture, with conversion of theolefin to an aldehyde.
 15. Process according to claim 14, characterizedin that the catalyst precursor comprises a ligand selected fromacetylacetonate, acetate and chloride.
 16. Process according to claim14, characterized in that the catalyst precursor is Rh(acac)(CO)₂.